1. Field of the Invention
The present invention relates to a vehicle seat, as well as an operating method for a vehicle seat.
2. Description of Related Art
In side collisions, injuries ranging from severe to fatal often occur to vehicle occupants on both sides of the vehicle, i.e. on the side facing both toward and away from the crash. A determination of the frequency of side collisions in which at least one person is sitting on the vehicle side facing toward the crash reveals this figure to be 70%, for whom an increased probability of injury exists. With regard to the vehicle side facing away from the crash, it is found that in approximately 65% of cases, at least one person was sitting on the vehicle side facing away from the crash.
A variety of restraint systems and structural solutions are used at present in vehicle engineering in order to reduce the consequences of side collisions. These include chiefly side airbags, for example curtain airbags, head airbags, or combined head/thorax airbags, or special stiffeners in the vehicle structure, for example sills or side impact protection systems. In the context of a side collision, the purpose of these systems is both to protect the occupants from contact with intruding vehicle parts on the direct crash side, and to dissipate some of the occupants' motion energy.
The thorax airbag or combined head/thorax airbag, which is installed on the outer side of the seat, on the B pillar, or increasingly often in the door region, typically serves as a first impact protection for the vehicle occupants. The triggering times for these airbag units are usually in the range from 5 to 8 ms after contact between the vehicle and an obstacle, or after a crash. Inflation times vary, depending on the airbag volume and the gas generator technology used, between 10 and 20 ms. In the most optimum case, a protective system of this kind should possess one hundred percent of its protective effect 15 ms after detection of the crash. The dwell time of this type of side airbag, which slides between the occupant or seat and the B-pillar or vehicle door, is 80 to 120 ms, especially since a rebound motion of the occupant away from the damaging structure has already started after that time period. In order to meet stringent requirements in terms of triggering time and inflation time, it is common to use combined pyrotechnic compressed-gas generators that, already at an early stage of activation of the generator (i.e. 2 to 5 ms after detection), possess sufficient energy to inflate the airbag. Starting at 5 to 10 ms, the compressed gas generator portion of the gas generator then ensures the required consistency in gas outflow.
A different situation is apparent with regard to head, window, or curtain airbags. These serve exclusively to protect the head. Considerably more time is therefore available to them for the inflation operation, but the airbag volume is also considerably greater. Their dwell time is also several times longer (5 seconds), since rollover accidents need to be accounted for.
With the introduction of new side crash regulations in the United State, the situation for vehicle manufacturers in terms of side crash performance will change considerably. According to these new regulations, an oblique pole crash at 32 km/h, in which a vehicle is rotated 15° with respect to the usual perpendicular crash direction, is now mandatory for all vehicles approved for the US market. This involves the use, for the first time, of a side crash test dummy representing a small female per SID-IIs. An improved EUROSID dummy per ES-2re is also stipulated. The overall goal of this new standard is to enhance head and thorax protection in a side impact. Preliminary studies have shown, however, that existing vehicles (with the exception of SUVs) must be adapted to these requirements and the corresponding injury criteria. A frequent problem is that in the aforementioned pole crash as defined by FMVSS213, the thorax airbag used to protect the thorax region may not inflate at all.
A further set of problems relates to the protection of occupants on the side facing away from the crash, for which the term “far side crash” is also used. Although attempts are being made to improve the performance of vehicle side structures by improving vehicle design, it is often impossible to ensure sufficient occupant protection by way of the vehicle structure on the vehicle side facing away from the crash. The consequence for a belted-in occupant sitting on the side of the vehicle facing away from the crash is often that he or she slides out of the seatbelt in the shoulder region because of insufficient tension uptake and thus insufficient friction between belt and occupant. The occupant is then immobilized essentially only by the lap belt, which prevents the occupant from being thrown out of the vehicle despite the diminished protective effect. Due to the insufficient immobilization of the occupant's torso, it can move more or less freely in the vehicle interior. The most common cause of injury as a result is collision with other occupants or, subsequently to rebound motion, collision with interior elements of the vehicle.
Given the accident scenario, restraint, systems at present are designed so that the side and head airbags are fired only on the vehicle side facing toward the crash, so that the occupant is not struck by intruding vehicle parts and so the airbag moves the occupant out of the danger zone. In the case of a rollover, it is usual for the head airbags provided for that purpose on both sides of the vehicle to fire, so that objects cannot penetrate from outside into the vehicle interior.
Solutions already exist for protecting occupants on the vehicle side facing away from the crash. German Utility Model DE 203 14 924 U1, for example, describes a safety assemblage for a vehicle occupant sitting on a vehicle seat, having a three-point safety belt that has a lap belt and shoulder belt. This safety assemblage contains an additional two-point shoulder belt that extends from the shoulder left exposed by the three-point safety belt and crosses the shoulder belt of the three-point safety belt. Because the risk exists, in a far side impact, that the occupant located on the side facing away from a crash may rotate out of the shoulder belt of the three-point safety belt as a result of force components acting from the interior of the vehicle, a two-point belt is additionally provided in this safety assemblage. This additional belt is also activated, in the shoulder region of the seatback, by way of an additional belt retractor, and crosses the shoulder belt of the three-point belt in the vehicle occupant's chest region. This additional two-point belt thus prevents the vehicle occupant from rotating out of the shoulder belt of the three-point belt.
A similar apparatus is described in German Patent DE 10 2005 002 393. This presents a vehicle occupant protection apparatus having a three-point safety belt in which the upper articulation, located in the vehicle occupant's shoulder region, for the shoulder belt, and the lower articulation for the lap belt, are located on the side of the vehicle seat facing away from the vehicle door that is adjacent to the vehicle seat. In addition, this system contains a side airbag that is disposed on the side of the vehicle seat facing toward the vehicle door and that deploys, upon triggering, between the vehicle door and vehicle occupant. This airbag is characterized in that it is equipped with a ventilation device, switchable on and off via a control apparatus, for the gas present in the inflated side airbag, and that the ventilation device is switched on upon detection of a side impact and is switched off upon detection of a vehicle rollover. Similar systems are described in published European Patent Application EP 1 470 969 A1.
A further solution proposes also to activate, after a corresponding delay, the lateral restraint means on the vehicle side facing away from the crash. This shows that further components of the safety equipment of modern vehicles possess a great deal of potential, to some extent not yet used, for protection in side crashes. One of these often-underestimated passive safety systems is the seat. In addition to the passive safety systems such as airbags, retractors, and belt tensioners, further systems that can improve the lateral retention of the occupants or also protect them better in the event of a collision are used in vehicles. These include sport seats having salient side flanks, or comfort seats that fill the side regions of the seat with air in a context of increased transverse acceleration. It is disadvantageous, however, that sport seats do not offer sufficient seating comfort for everyone, and are therefore less often installed in vehicles. A further disadvantage of these active, adaptable seats is that they operate on a very different time scale from the one necessary in the event of a crash, i.e. in the event of a crash it is not possible to trigger these systems within a timeframe suitable for protection. Dynamic seats of this kind nevertheless offer the advantage that as a result of the prior so-called “vehicle-dynamics” activation of the seat, the occupant is kept away from the side structure of the vehicle if the vehicle is carried out of a curve in the event of a skid. An alternative implementation of a vehicle-dynamics seat is, for example, a seat having a two-part backrest based on a “split-seat” concept. This seat follows the motions of the torso in every seat position, and ensures optimum relief of load on the spine. For example, if the driver leans back in the seat, the lower part of the backrest automatically pivots forward and supports the pelvis.
It is evident in this context that crash-active systems in the seat offer a great deal of potential for occupant protection in side crashes. A feature common to all the known solutions is that existing side elements and seat elements are moved or positioned in corresponding fashion. This occurs predominantly by inflation of the side bolsters in the case of an imminent side collision, or even after a contact. In all the systems presented, however, an additional apparatus that provides a safety belt or an additional airbag in the inner seat region is needed.